1. Field of the Invention
The invention relates to a two cycle engine and to a tool using the two cycle engine.
2. Description of the Related Art
By reason of their high specific output, position-independent usability and their low weight two cycle engines of this type are preferably used in tools, in particular hand-held tools.
In essence, two principles are known for the lubrication of two cycle engines, namely petroil lubrication, in which oil is admixed beforehand to the fuel at a mixing ratio of 1:25 to 1:100, and separate-lubrication, in which oil is pumped from a separate oil tank by means of an oil pump into the crank housing or the carburettor nozzle. Both lubricating methods help make it possible to utilise two cycle engines in any position and also serve to keep the weight of such engines low.
Whereas with petroil lubrication the oil must be added to the fuel during each fuelling procedure, it is necessary in the separate-lubricating process to top up the separate oil tank at regular intervals, as in the case of two cycle engines there is basically a loss lubrication, i.e. there is no oil circulation. A certain portion of the oil thus does not contribute to the lubrication but is burnt without having been used. An excessively large amount of oil therefore has to be supplied to the engine, which not least increases the total weight of the two cycle engine by reason of the oil reserve.
A two cycle engine is known from U.S. Pat. No. 4,794,896 A in which oil can be discharged via an oil outlet into the region of a contact surface between a piston and a cylinder.